Multi-speed transmission

ABSTRACT

A transmission is provided having an input member, an output member, four planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. The torque transmitting devices are clutches and brakes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/949,261 filed on Jul. 12, 2007. The disclosure of the aboveapplication is incorporated herein by reference.

FIELD

The invention relates generally to a multiple speed transmission havinga plurality of planetary gear sets and a plurality of torquetransmitting devices and more particularly to a transmission having nineor more speeds, four planetary gear sets and a plurality of torquetransmitting devices.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed transmission uses a combination of frictionclutches, planetary gear arrangements and fixed interconnections toachieve a plurality of gear ratios. The number and physical arrangementof the planetary gear sets, generally, are dictated by packaging, costand desired speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved transmission configurations which exhibit improvedperformance, especially from the standpoints of efficiency,responsiveness and smoothness and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needfor an improved, cost-effective, compact multiple speed transmission.

SUMMARY

A transmission is provided having an input member, an output member,four planetary gear sets, a plurality of coupling members and aplurality of torque transmitting devices. Each of the planetary gearsets includes first, second and third members. The torque transmittingdevices are for example clutches and brakes.

An embodiment of the transmission includes an input member, an outputmember, first, second, third and fourth planetary gear sets each havingfirst, second and third members. A first interconnecting membercontinuously interconnects the first member of the first planetary gearset with the first member of the third planetary gear set, a secondinterconnecting member continuously interconnects the third member ofthe first planetary gear set with the second member of the secondplanetary gear set, a third interconnecting member continuouslyinterconnects the third member of the second planetary gear set with thesecond member of the third planetary gear set and the output member, anda fourth interconnecting member continuously interconnects the thirdmember of the third planetary gear set and the second member of thefourth planetary gear set. Six torque transmitting mechanisms areselectively engageable to interconnect one of the first, second, andthird members with at least one of the first members, second members,third members, and a stationary element. The torque transmittingmechanisms are selectively engageable in combinations of at least threeto establish at least nine forward speed ratios and at least one reversespeed ratio between the input member and the output member.

In one aspect of the present invention, a first of the six torquetransmitting mechanisms is selectively engageable to interconnect atleast one of the input member and the third member of the fourthplanetary gear set with the first member of the fourth planetary gearset.

In another aspect of the present invention, a second of the six torquetransmitting mechanisms is selectively engageable to interconnect thefirst member of the second planetary gear set with the first member ofthe fourth planetary gear set.

In yet another aspect of the present invention, a third of the sixtorque transmitting mechanisms is selectively engageable to interconnectat least one of the second member of the second planetary gear set andthe third member of the first planetary gear set with at least one ofthe third member of the third planetary gear set and the second memberof the fourth planetary gear set.

In yet another aspect of the present invention, a fourth of the sixtorque transmitting mechanisms is selectively engageable to interconnectthe first member of the second planetary gear set with a stationaryelement.

In yet another aspect of the present invention, a fifth of the sixtorque transmitting mechanisms is selectively engageable to interconnectthe second member of the first planetary gear set with the stationaryelement.

In yet another aspect of the present invention, a sixth of the sixtorque transmitting mechanisms is selectively engageable to interconnectat least one of the first member of the first planetary gear set and thefirst member of the third planetary gear set with the stationaryelement.

In yet another aspect of the present invention, the first members aresun gears, the second members are carrier members, and the third membersare ring gears.

In yet another aspect of the present invention, the input member iscontinuously interconnected with the third member of the fourthplanetary gear set and wherein the output member is continuouslyinterconnected with at least one of the second member of the thirdplanetary gear set and the third member of the second planetary gearset.

In yet another aspect of the present invention, three of the torquetransmitting mechanisms are brakes and three of the torque transmittingmechanisms are clutches.

In yet another aspect of the present invention, the stationary elementis a transmission housing.

Another embodiment of the transmission of the present invention includesan input member, an output member, first, second, third and fourthplanetary gear sets each having first, second and third members, whereinthe input member is continuously interconnected with the third member ofthe fourth planetary gear set and wherein the output member iscontinuously interconnected with at least one of the second member ofthe third planetary gear set and the third member of the secondplanetary gear set. A first interconnecting member continuouslyinterconnects the first member of the first planetary gear set with thefirst member of the third planetary gear set, a second interconnectingmember continuously interconnects the third member of the firstplanetary gear set with the second member of the second planetary gearset, a third interconnecting member continuously interconnects the thirdmember of the second planetary gear set with the second member of thethird planetary gear set and the output member, and a fourthinterconnecting member continuously interconnects the third member ofthe third planetary gear set and the second member of the fourthplanetary gear set. A first torque transmitting mechanism is selectivelyengageable to interconnect at least one of the input member and thethird member of the fourth planetary gear set with the first member ofthe fourth planetary gear set. A second torque transmitting mechanism isselectively engageable to interconnect the first member of the secondplanetary gear set with the first member of the fourth planetary gearset. A third torque transmitting mechanism is selectively engageable tointerconnect at least one of the second member of the second planetarygear set and the third member of the first planetary gear set with atleast one of the third member of the third planetary gear set and thesecond member of the fourth planetary gear set. A fourth torquetransmitting mechanism is selectively engageable to interconnect thefirst member of the second planetary gear set with a stationary element.A fifth torque transmitting mechanism is selectively engageable tointerconnect the second member of the first planetary gear set with thestationary element. A sixth torque transmitting mechanism is selectivelyengageable to interconnect at least one of the first member of the firstplanetary gear set and the first member of the third planetary gear setwith the stationary element. The torque transmitting mechanisms areselectively engageable in combinations of at least three to establish atleast nine forward speed ratios and at least one reverse speed ratiobetween the input member and the output member.

In one aspect of the present invention, first members are sun gears, thesecond members are carrier members, and the third members are ringgears.

In another aspect of the present invention, the stationary element is atransmission housing.

Another embodiment of the transmission of the present invention includesan input member, an output member, first, second, third and fourthplanetary gear sets each having a sun gear, a carrier member, and a ringgear, wherein the input member is continuously interconnected with thering gear of the fourth planetary gear set and wherein the output memberis continuously interconnected with at least one of the carrier memberof the third planetary gear set and the ring gear of the secondplanetary gear set. A first interconnecting member continuouslyinterconnects the sun gear of the first planetary gear set with the sungear of the third planetary gear set, a second interconnecting membercontinuously interconnects the ring gear of the first planetary gear setwith the carrier member of the second planetary gear set, a thirdinterconnecting member continuously interconnects the ring gear of thesecond planetary gear set with the carrier member of the third planetarygear set and the output member, and a fourth interconnecting membercontinuously interconnects the ring gear of the third planetary gear setand the carrier member of the fourth planetary gear set. A first torquetransmitting mechanism is selectively engageable to interconnect atleast one of the input member and the ring gear of the fourth planetarygear set with the sun gear of the fourth planetary gear set. A secondtorque transmitting mechanism is selectively engageable to interconnectthe sun gear of the second planetary gear set with the sun gear of thefourth planetary gear set. A third torque transmitting mechanism isselectively engageable to interconnect at least one of ring gear of thefirst planetary gear set and the carrier member of the second planetarygear set with at least one of the ring gear of the third planetary gearset and the carrier member of the fourth planetary gear set. A fourthtorque transmitting mechanism is selectively engageable to interconnectthe sun gear of the second planetary gear set with a stationary element.A fifth torque transmitting mechanism is selectively engageable tointerconnect the carrier member of the first planetary gear set with thestationary element. A sixth torque transmitting mechanism is selectivelyengageable to interconnect at least one of the sun gear of the firstplanetary gear set and the sun gear of the third planetary gear set withthe stationary element. The torque transmitting mechanisms areselectively engageable in combinations of at least three to establish atleast nine forward speed ratios and at least one reverse speed ratiobetween the input member and the output member.

In one aspect of the present invention, the stationary element is atransmission housing.

Further objects, aspects and advantages of the present invention willbecome apparent by reference to the following description and appendeddrawings wherein like reference numbers refer to the same component,element or feature.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a lever diagram of an embodiment of a nine speed transmissionaccording to the present invention;

FIG. 2 is a diagrammatic view of an embodiment of a nine speedtransmission according to the present invention; and

FIG. 3 is a truth table presenting the state of engagement of thevarious torque transmitting devices in each of the available forward andreverse speeds or gear ratios of the transmission illustrated in FIGS. 1and 2.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

At the outset, it should be appreciated that in the particular exampleprovided, the nine speed automatic transmission of the present inventionhas an arrangement of permanent mechanical connections between theelements of the four planetary gear sets. A first component or elementof a first planetary gear set is permanently coupled to a firstcomponent or element of a third planetary gear set. A third component orelement of the first planetary gear set is permanently coupled to asecond component or element of a second planetary gear set. A firstcomponent or element of the second planetary gear set is permanentlycoupled to a second component or element of the third planetary gearset. Finally, a third component or element of the third planetary gearset is permanently coupled to a second component or element of a fourthplanetary gear set.

Referring now to FIG. 1, an embodiment of a nine speed transmission 10is illustrated in a lever diagram format. A lever diagram is a schematicrepresentation of the components of a mechanical device such as anautomatic transmission. Each individual lever represents a planetarygear set wherein the three basic mechanical components of the planetarygear set are each represented by a node. Therefore, a single levercontains three nodes: one for the sun gear, one for the planet gearcarrier, and one for the ring gear. The relative length between thenodes of each lever can be used to represent the ring-to-sun ratio ofeach respective gear set. These lever ratios, in turn, are used to varythe gear ratios of the transmission in order to achieve appropriateratios and ratio progression. Mechanical couplings or interconnectionsbetween the nodes of the various planetary gear sets are illustrated bythin, horizontal lines and torque transmitting devices such as clutchesand brakes are presented as interleaved fingers. If the device is abrake, one set of the fingers is grounded. Further explanation of theformat, purpose and use of lever diagrams can be found in SAE Paper810102, “The Lever Analogy: A New Tool in Transmission Analysis” byBenford and Leising which is hereby fully incorporated by reference.

The transmission 10 includes an input shaft or member 12, a firstplanetary gear set 14 having three nodes: a first node 14A, a secondnode 14B and a third node 14C, a second planetary gear set 16 havingthree nodes: a first node 16A, a second node 16B and a third node 16C, athird planetary gear set 18 having three nodes: a first node 18A, asecond node 18B and a third node 18C, a fourth planetary gear set 20having three nodes: a first node 20A, a second node 20B and a third node20C and an output shaft or member 22.

The input shaft or member 12 is coupled to the third node 20C of thefourth planetary gear set 20. The output shaft or member 22 is coupledto the second node 18B of the third planetary gear set 18. The firstnode 14A of the first planetary gear set 14 is coupled to the first node18A of the third planetary gear set 18. The third node 14C of the firstplanetary gear set 14 is coupled to the second node 16B of the secondplanetary gear set 16. The first node 16A of the second planetary gearset 16 is coupled to the second node 18B of the third planetary gear set18. The third node 18C of the third planetary gear set 18 is coupled tothe second node 20B of the fourth planetary gear set 20.

A first clutch 26 selectively connects the first node 20A of the fourthplanetary gear set 20 to the third node 20C of the fourth planetary gearset 20 and to the input shaft or member 12. A second clutch 28selectively connects third node 16C of the second planetary gear set 16to the first node 20A of the fourth planetary gear set 20. A thirdclutch 30 selectively connects the second node 16B of the secondplanetary gear set 16 to the second node 20B of the fourth planetarygear set 20 and to the third node 18C of the third planetary gear set18. A first brake 32 selectively connects the third node 16C of thesecond planetary gear set 16 to a ground or a transmission housing 50. Asecond brake 34 selectively connects the second node 14B of the firstplanetary gear set 14 to a ground or a transmission housing 50. A thirdbrake 36 selectively connects the first node 18A of the third planetarygear set 18 to a ground or a transmission housing 50.

Referring now to FIG. 2, a stick diagram presents a schematic layout ofthe embodiment of the nine speed transmission 10 according to thepresent invention. In FIG. 2, the numbering from the lever diagram ofFIG. 1 is carried over. The clutches, brakes and couplings arecorrespondingly presented whereas the nodes of the planetary gear setsnow appear as components of planetary gear sets such as sun gears, ringgears, planet gears and planet gear carriers.

For example, the planetary gear set 14 includes a sun gear member 14A, aplanet gear carrier member 14B that supports a set of planet gears 14Dand a ring gear member 14C. The sun gear member 14A is connected forcommon rotation with a first shaft or interconnecting member 42 and asecond shaft or interconnecting member 44. The ring gear member 14C isconnected for common rotation with a third shaft or interconnectingmember 46. The planet gear carrier member 14B is connected for commonrotation with a fourth shaft or interconnecting member 48. The planetgears 14D are each configured to intermesh with both the ring gearmember 14C and the sun gear member 14A.

The input shaft or member 12 is preferably continuously connected to anengine (not shown) or to a turbine of a torque converter (not shown).The output shaft or member 22 is preferably continuously connected withthe final drive unit or transfer case (not shown).

The planetary gear set 16 includes a sun gear member 16C, a ring gearmember 16A and a planet carrier member 16B that rotatably supports a setof planet gears 16D. The sun gear member 16C is connected for commonrotation with a fifth shaft or interconnecting member 52 and a sixthshaft or interconnecting member 54. The ring gear member 16A isconnected for common rotation with a seventh shaft or interconnectingmember 56. The planet carrier member 16B is connected for commonrotation with the third shaft or interconnecting member 46 and a ninthshaft or interconnecting member 59. The planet gears 16D are eachconfigured to intermesh with both sun gear member 16C and ring gearmember 16A.

The planetary gear set 18 includes a sun gear member 18A, a ring gearmember 18C and a planet carrier member 18B that rotatably supports a setof planet gears 18D. The sun gear member 18A is connected for commonrotation with the first shaft or interconnecting member 42. The ringgear member 18C is connected for common rotation with a tenth shaft orinterconnecting member 60. The planet carrier member 18B is connectedfor common rotation with the seventh shaft or interconnecting member 56and with output shaft or member 22. The planet gears 18D are eachconfigured to intermesh with both the sun gear member 18A and the ringgear member 18C.

The planetary gear set 20 includes a sun gear member 20A, a planetcarrier member 20B that rotatably supports a set of planet gears 20D,and a ring gear member 20C. The sun gear member 20A is connected forcommon rotation with an eleventh shaft or interconnecting member 62. Theplanet carrier member 20B is connected for common rotation with thetenth shaft or interconnecting member 60. The ring gear member 20C isconnected for common rotation with input shaft or member 12. The planetgears 20D are each configured to intermesh with both the ring gearmember 20C and sun gear member 20A.

The torque transmitting mechanisms or clutches 26, 28, 30, and brakes32, 34 and 36 allow for selective interconnection of the shafts orinterconnecting members, members of the planetary gear sets and thehousing 50. For example, the first clutch 26 is selectively engageableto connect the input shaft or member 12 to the eleventh shaft orinterconnecting member 62. The second clutch 28 is selectivelyengageable to connect the sixth shaft or interconnecting member 54 tothe eleventh shaft or interconnecting member 62. The third clutch 30 isselectively engageable to connect the ninth shaft or interconnectingmember 59 to the tenth shaft or interconnecting member 60. The firstbrake 32 is selectively engageable to connect sun gear member 16C viafifth shaft or interconnecting member 52 to ground, a stationaryelement, or transmission housing 50 to restrict rotation of sun gearmember 16C relative to transmission housing 50. The second brake 34 isselectively engageable to connect planet carrier member 14B via fourthshaft or interconnecting member 48 to ground, a stationary element, ortransmission housing 50 to restrict rotation of planet carrier member14B relative to transmission housing 50. The third brake 36 isselectively engageable to connect sun gear members 14A, 18A via firstshaft or interconnecting member 42 and second shaft or interconnectingmember 44 to ground, a stationary element, or transmission housing 50 torestrict rotation of sun gear members 14A, 18A relative to transmissionhousing 50.

In the present embodiment, the third clutch 30 and second brake 34 arelarger than clutches 26, 28 and brakes 32, 36. For example, the thirdclutch 30 and second brake 34 have increased diameter friction plates ora greater number of friction plates thus providing additional functionalfriction surface area than the clutches 26, 28 and brakes 32, 36. Thelarger clutch 30 and brake 34 allow for increased torque transmittingcapacity, shorter engagement time, and improved wear characteristics.However, the present invention contemplates that other embodiments haveclutches and brakes 26, 28, 30, 32, 34, and 36 of different sizeswithout departing from the scope of the present invention.

Referring now to FIGS. 2 and 3, the operation of the embodiment of thenine speed transmission 10 will be described. It will be appreciatedthat transmission 10 is capable of transmitting torque from the inputshaft or member 12 to the output shaft or member 22 in at least nineforward speed or torque ratios and at least one reverse speed or torqueratio with a double overdrive. Each forward and reverse speed or torqueratio is attained by engagement of one or more of thetorque-transmitting mechanisms (i.e. first clutch 26, second clutch 28,third clutch 30, first brake 32, second brake 34 and third brake 36), aswill be explained below. FIG. 3 is a truth table presenting the variouscombinations of torque-transmitting mechanisms that are activated orengaged to achieve the various gear states. Actual numerical gear ratiosof the various gear states are also presented although it should beappreciated that these numerical values are exemplary only and that theymay be adjusted over significant ranges to accommodate variousapplications and operational criteria of the transmission 10. An exampleof the gear ratios that may be obtained using the embodiments of thepresent invention are also shown in FIG. 3. Of course, other gear ratiosare achievable depending on the gear diameter, gear teeth count and gearconfiguration selected.

To establish reverse gear, the first clutch 26, the third clutch 30 andthe second brake 34 are engaged or activated. The first clutch 26connects the input shaft or member 12 to the eleventh shaft orinterconnecting member 62. The third clutch 30 connects the ninth shaftor interconnecting member 59 to tenth shaft or interconnecting member60. The second brake 34 connects planet carrier member 14B via fourthshaft or interconnecting member 48 to ground, a stationary element, ortransmission housing 50 to restrict rotation of planet carrier member14B relative to transmission housing 50. Likewise, the nine forwardratios are achieved through different combinations of clutch and brakeengagement, as shown in FIG. 3.

It will be appreciated that the foregoing explanation of operation andgear states of the nine speed transmission 10 assumes, first of all,that all the clutches not specifically referenced in a given gear stateare inactive or disengaged and, second of all, that during gear shifts,i.e., changes of gear state, between at least adjacent gear states, aclutch or brake engaged or activated in both gear states will remainengaged or activated.

The description of the invention is merely exemplary in nature andvariations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A transmission comprising: an input member; an output member; first,second, third and fourth planetary gear sets each having first, secondand third members, wherein the input member is continuouslyinterconnected with the third member of the fourth planetary gear setand wherein the output member is continuously interconnected with thesecond member of the third planetary gear set and the third member ofthe second planetary gear set; a first interconnecting membercontinuously interconnecting the first member of the first planetarygear set with the first member of the third planetary gear set; a secondinterconnecting member continuously interconnecting the third member ofthe first planetary gear set with the second member of the secondplanetary gear set; a third interconnecting member continuouslyinterconnecting the third member of the second planetary gear set withthe second member of the third planetary gear set and the output member;a fourth interconnecting member continuously interconnecting the thirdmember of the third planetary gear set and the second member of thefourth planetary gear set; a first torque transmitting mechanismselectively engageable to interconnect the third member of the fourthplanetary gear set with the first member of the fourth planetary gearset; a second torque transmitting mechanism selectively engageable tointerconnect the first member of the second planetary gear set with thefirst member of the fourth planetary gear set; a third torquetransmitting mechanism selectively engageable to interconnect the secondmember of the second planetary gear set and the third member of thefirst planetary gear set with the third member of the third planetarygear set and the second member of the fourth planetary gear set; afourth torque transmitting mechanism selectively engageable tointerconnect the first member of the second planetary gear set with astationary element; a fifth torque transmitting mechanism selectivelyengageable to interconnect the second member of the first planetary gearset with the stationary element; and a sixth torque transmittingmechanism selectively engageable to interconnect the first member of thefirst planetary gear set and the first member of the third planetarygear set with the stationary element, and wherein the torquetransmitting mechanisms are selectively engageable in combinations of atleast three to establish at least nine forward speed ratios and at leastone reverse speed ratio between the input member and the output member.2. The transmission of claim 1 wherein the first members are sun gears,the second members are carrier members, and the third members are ringgears.
 3. The transmission of claim 1 wherein the stationary element isa transmission housing.
 4. A transmission comprising: an input member;an output member; first, second, third and fourth planetary gear setseach having a sun gear, a carrier member, and a ring gear, wherein theinput member is continuously interconnected with the ring gear of thefourth planetary gear set and wherein the output member is continuouslyinterconnected with the carrier member of the third planetary gear setand the ring gear of the second planetary gear set; a firstinterconnecting member continuously interconnecting the sun gear of thefirst planetary gear set with the sun gear of the third planetary gearset; a second interconnecting member continuously interconnecting thering gear of the first planetary gear set with the carrier member of thesecond planetary gear set; a third interconnecting member continuouslyinterconnecting the ring gear of the second planetary gear set with thecarrier member of the third planetary gear set and the output member; afourth interconnecting member continuously interconnecting the ring gearof the third planetary gear set and the carrier member of the fourthplanetary gear set; a first torque transmitting mechanism selectivelyengageable to interconnect the ring gear of the fourth planetary gearset with the sun gear of the fourth planetary gear set; a second torquetransmitting mechanism selectively engageable to interconnect the sungear of the second planetary gear set with the sun gear of the fourthplanetary gear set; a third torque transmitting mechanism selectivelyengageable to interconnect the ring gear of the first planetary gear setand the carrier member of the second planetary gear set with the ringgear of the third planetary gear set and the carrier member of thefourth planetary gear set; a fourth torque transmitting mechanismselectively engageable to interconnect the sun gear of the secondplanetary gear set with a stationary element; fifth torque transmittingmechanism selectively engageable to interconnect the carrier member ofthe first planetary gear set with the stationary element; and a sixthtorque transmitting mechanism selectively engageable to interconnect thesun gear of the first planetary gear set and the sun gear of the thirdplanetary gear set with the stationary element, and wherein the torquetransmitting mechanisms are selectively engageable in combinations of atleast three to establish at least nine forward speed ratios and at leastone reverse speed ratio between the input member and the output member.5. The transmission of claim 4 wherein the stationary element is atransmission housing.